White Paper Analysis of the 'Conflict Minerals' Columbite-Tantalite Using

White Paper

Analysis of the ‘Conflict Minerals’ Columbite-Tantalite Using Laser-induced Breakdown Spectroscopy (LIBS)

Applied Spectra Inc - 27 May 2011

Background

Conflict minerals is a term applied to ores mined in conditions of armed conflict and human rights abuse. Niobium and tantalum are two rare metals whose primary natural occurrence is in the complex oxide minerals columbite and tantalite, the ore of which is commonly referred to as “coltan”. Niobium (Nb) and tantalum (Ta) are rare metals of commercial value and the high demand for these elements has resulted in an increase in exploration programs to locate new ore deposits. At present, the predominant supply of the world's columbite-tantalite ore comes from Brazil and Australia. However, columbite-tantalite occurs in many areas of Central Africa, with some 60% of the world’s Ta ore reserves located in the eastern portion of Democratic Republic of Congo (DRC) and adjacent areas. Although the overall production of Nb and Ta in Central Africa is relatively small at present, the illicit export and sale of columbite and tantalite from the DRC to European and North American markets has been cited as an important means by which the civil conflicts in Central Africa are being financed.

Current Situation

At present, there is no analytical technique by which an analysis to determine the place of origin of coltan ore can be accomplished rapidly in the field.

Proposal

We have investigated the use of laser-induced breakdown spectroscopy (LIBS) to meet this challenge based on the concept of ‘geochemical fingerprinting’. Laboratory scale validation of the technology will be completed (and published) by the middle of summer 2011.The idea is that the LIBS emission spectrum provides a unique chemical signature of a material that can be used to discriminate geological specimens originating in one place from samples of the same kind from other locations. Identification is based upon the fact that the Earth’s crust is compositionally heterogeneous and that minerals forming within the crust will reflect that intrinsic geographic heterogeneity. LIBS offers a means of rapidly distinguishing different geographic sources for a mineral because the LIBS plasma emission spectrum provides the complete chemical composition (i.e. a ‘chemical fingerprint’) of any material in real-time. LIBS has already been proven to work in the field for other applications.

Columbite-tantalite samples from North America, South America, Africa, and Asia have been examined by LIBS using laboratory-based and field portable instruments. The data was analyzed using chemometric techniques such as partial least squares discriminant analysis (PLSDA) to demonstrate that LIBS can rapidly distinguish different geographic sources with LIBS spectra with high levels of certainty. A paper describing the preliminary studies has recently appears (Harmon, R.S., Shughrue, K.M., Remus, J.J., Wise, M.A., East, L.J., Hark, R.R. “Can the provenance of the conflict minerals columbite-tantalite be ascertained by laser-induced breakdown spectroscopy?” Anal. Bioanal. Chem., 2011, DOI 10.1007/s00216-011-5015-2). Additional work with a larger, more geographically diverse and fully validated sample suite and optimization of spectral acquisition parameters is currently underway. Samples of processed coltan ore from actual areas of conflict in central Africa are also being obtained for testing.

LIBS holds great promise as a means to provenance “conflict” coltan as well as other conflict minerals found in abundance in the region such as cassiterite (tin ore), wulframite (tungsten ore) and gold. The buying rules related to Congolese minerals recently adopted by the global electronics industry have caused considerable hardship in the region for hundreds of thousands of people involved in the mining industry in that region. This makes finding a solution to the traceability problem all the more imperative.

Following the current on-going technical (R&D) investigation, the research team proposes a 6 month Engineering and Demonstration effort (T&E) to mature and demonstrate the Applied Spectra Inc field-portable LIBS instrumentation in mining and ore processing sites world-wide.

The research team includes:

Richard Russo, Lucille J. East Applied Spectra Inc, 46661 Fremont Blvd., Fremont, CA 94538

Richard R. Hark, Katrina Shughrue Department of Chemistry, Juniata College, Huntingdon, PA 16652 Russell S. Harmon ARL Army Research Office, PO Box 12211, Research Triangle Park, NC 27709 Jeremiah J. Remus Department of Electrical and Computer Engineering, Clarkson University, Potsdam, NY 13699 Michael A. Wise Division of Mineralogy, Smithsonian Institution, PO Box 37012, MRC 119, Washington, DC 20013

POC Applied Spectra Inc - NH Contact: John Plumer - (603) 387-7765, Dr Richard Russo - Applied Spectra Inc. CA, [email protected]

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